The Vikings.com 2018 Free Agency Primer series uses NFL.com’s Top 101 Free Agents list to break down this year’s class. We will count down the groups of players until March 14 when free agency is scheduled to open.

The list was composed by Gregg Rosenthal and Chris Wesseling of NFL.com. Career stats are taken from NFL.com and/or pro-football-reference.com and apply to regular seasons, unless noted.

Note: The list may end up changing prior to free agency opening, but this breakdown is updated as of March 5.

A variety of experience runs deep in this grouping that includes three players from NFC North squads: Detroit’s Tahir Whitehead and Chicago’s Prince Amukamara and Josh Sitton.

Five of the players in this group — Whitehead, Amukamara, Sitton, Brent Grimes and Josh McCown — have appeared in at least 83 regular-season games. McCown is the oldest but has been more active in the past few seasons than earlier in his career.

A fifth-round pick in 2012, Whitehead has appeared in all but three games in six seasons for the Lions. He became a starter in 2014 and helped Detroit rank second in the NFL in yards allowed and third in points against. Whitehead started nine games the following season and has totaled 242 tackles in the past two seasons (started all 31 games played).

Initially signed as an undrafted free agent by Green Bay and waived with an injury settlement in 2006, Grimes began a productive and prolonged career on Atlanta’s practice squad. He missed the initial roster in 2007 but was signed to the Falcons practice squad during the season. After six years with Atlanta that included one Pro Bowl, Grimes turned in three consecutive Pro Bowl seasons with Miami. Grimes totaled seven interceptions and started all 29 games he played for Tampa Bay the past two seasons.

Richardson, a second-round pick in 2014 (45th overall), did most of his statistical damage in 2017 with his first opportunity to be a full-time starter. The field stretcher posted 44 receptions for 703 yards (16.0 yards per reception) and six touchdowns, but his catch percentage of 55.0 was a career-low.

The sixth overall pick of the 2012 NFL Draft by Dallas, Claiborne moved on from the Cowboys last offseason and landed with the Jets in free agency. Claiborne started all 15 games for the second time in his career and tied his career high of eight passes defensed in 2017.

After spending his first five seasons with the Giants as their first-round pick in 2011, Amukamara has had consecutive one-year deals in Jacksonville and Chicago. His production at both stops were nearly carbon copies:

McCown, who will turn 39 on July 4, has started 35 games with three different teams in the past four seasons (Buccaneers, Browns and Jets). In 2017, his first with the Jets, McCown had career highs in completions (267), completion percentage (67.3), yards (2,926) and passing touchdowns (18). He also took 39 sacks, which was one fewer than he did from 2006 through 2012 when he was primarily a backup QB for the Lions, Raiders, Panthers and Bears.

Brown recorded a career-best 144 tackles in 2017, which tied for the league lead, according to NFL statistics.

50. G Josh Sitton, Bears

147 career games; 137 starts

Sitton played in 121 of 128 possible games in eight seasons in Green Bay (2008-15), and he missed just two games after becoming a starter in 2009. He made three Pro Bowls with the Packers and another with the Bears after the 2016 season.